The present invention relates to polymer blends that exhibit properties useful in tape backing compositions. The tape backing compositions are useful in forming films, such as tape backings in auto paint masking tape.
Polyvinyl chloride (PVC) films and tapes are conventionally used for a wide variety of applications. One prevalent use is for auto paint masking applications. PVC has many properties that are advantageous for such applications. For example, PVC films are known to be conformable to the varying topographies present on an automobile""s exterior.
One disadvantage of PVC films, however, is the accompanying use of plasticizers in PVC films. Plasticizers are typically needed in PVC films in order to make the films more flexible, lower the glass transition temperature of the films, and make the films more conformable. However, plasticizers can migrate to the substrate on which PVC films are adhered, leaving a residue or xe2x80x9cghostingxe2x80x9d when removed. The ghosting is not removable with solvent wipes. Thus, the exterior appearance of the automobile may be detrimentally affected when PVC films are used as the tape backing in auto paint masking tapes. Furthermore, such plasticizers may degrade adjacent adhesive layers, reducing the adherence of the tape to the automobile.
It is desired to have alternative compositions for use in tape backings and films. It is particularly desired to have alternative compositions for use in auto paint masking tapes, where ghosting is often associated with conventional tapes.
Tape backing compositions of the present invention comprise a blend of a first and second polymer, the two polymers having a melting temperature of at least about 93xc2x0 C. (200xc2x0 F.), more preferably at least about 149xc2x0 C. (300xc2x0 F.), even more preferably at least about 154xc2x0 C. (310xc2x0 F.). Generally, one of the two polymers is more flexible than the other polymer. For example, in one embodiment, the first polymer has an elastic modulus of about 103 MPa or less and the second polymer has an elastic modulus of about 207 MPa or more. Typically, each of the first and second polymers comprises at least about 20 weight %, more preferably at least about 40 weight %, of the blend. It is preferred that each of the polymers in the blend is compatible. Thus, for example, preferably the blend exhibits a single melting temperature.
Accordingly, in one embodiment, the two polymers are polypropylene polymers. Typically, at least one of the polypropylene polymers is more flexible than the other polypropylene polymer. Thus, for example, a first polypropylene polymer can be at least about 20% atactic, more preferably about 25% atactic to about 50% atactic, and a second polypropylene polymer can be at least about 80% syndiotactic and/or isotactic. In another embodiment, the two polymers are polyester polymers. In yet another embodiment, the two polymers are polyamide polymers.
Tape backing compositions of the present invention are especially useful for making flexible films. Such films advantageously possess properties particularly useful for applications involving elevated temperatures, such as auto paint masking tape applications. For example, certain flexible films of the present invention exhibit less than about 5%, more preferably less than about 2%, shrinkage when tested according to ASTM D1204 at 93xc2x0 C. (200xc2x0 F.) and 149xc2x0 C. (300xc2x0 F.). Furthermore, certain flexible films of the present invention preferably exhibit greater than about 20% stress relaxation when tested at 10% elongation and/or greater than about 40% stress relaxation when tested at 57% elongation. Another preferred property is where the flexible films exhibit less than about 5% necking and/or where the films exhibit essentially no yield point when tested according to ASTM D882-95a. Also preferred are certain flexible films that are hand-tearable. In order to accomplish certain of the above properties, preferably the flexible films are heat-treated.
Typically, flexible films according to the present invention possess more than one of the above-described properties. For example, one particularly preferred flexible film of the present invention comprises a first polymer having a melting temperature of at least about 149xc2x0 C. (300xc2x0 F.); and a second polymer having a melting temperature of at least about 149xc2x0 C. (300xc2x0 F.), wherein the film exhibits less than about 5% shrinkage when tested according to ASTM D1204 at 149xc2x0 C. (300xc2x0 F.), the film exhibits greater than about 40% stress relaxation when tested at 10% elongation, the film exhibits greater than about 55% stress relaxation when tested at 57% elongation, and the film exhibits essentially no yield point when tested according to ASTM D882-95a.
Tapes comprising the flexible films include a backing of the flexible film; and an adhesive coated on at least a portion of one side of the backing for adherence to a substrate. Tapes of the present invention, like flexible films, may optionally be heat-treated. As compared to conventional polyvinyl chloride-containing tapes, tapes of the present invention can be prepared such that they exhibit essentially no ghosting when used, for example, as paint masking tapes on substrates exposed to elevated temperatures.
In one application, an auto paint masking tape comprises a chloride-free backing comprising a blend comprising at least one relatively inflexible polymer and at least one relatively flexible polymer and an adhesive coated on at least a portion of one side of the backing for adherence to an automobile. In another embodiment, an auto paint masking tape comprises a backing comprising a blend comprising at least one relatively inflexible polymer and at least one relatively flexible polymer; and an adhesive coated on at least a portion of one side of the backing for adherence to an automobile, wherein the backing is essentially free of plasticizers.
Auto paint masking tapes of the present invention can be effectively used on automobiles for masking paint thereon. For example, selected portions of an automobile can be protected from paint during painting of the automobile by adhering such an auto paint masking tape to the selected portions of the automobile, painting the automobile, and removing the auto paint masking tape from the selected portions of the automobile.
Tape backing compositions of the present invention comprise a polymer blend that includes at least two polymers. Preferably, at least one of the polymers is relatively flexible and at least one of the polymers is relatively inflexible. It is to be understood, however, that outside of the context of the present invention, all polymers in the blend may be considered flexible.
A polymer""s flexibility, as used herein, is measured in relation to the other polymer(s) in the blend. Any suitable method can be utilized for measuring the flexibility of a polymer. For example, the modulus (e.g., Young""s modulus) of a polymer has been found to correlate to a polymer""s flexibility.
As used herein, xe2x80x9crelatively flexible polymersxe2x80x9d generally have a relatively low Young""s modulus as compared to other polymer(s) in the blend. For example, preferably, the Young""s modulus of relatively flexible polymers herein is less than about 207 MPa (30,000 psi), more preferably less than about 103 MPa (15,000 psi), even more preferably less than about 34 MPa (5,000 psi).
As used herein, xe2x80x9crelatively inflexible polymersxe2x80x9d generally have a relatively high Young""s modulus as compared to other polymer(s) in the blend. For example, preferably, the Young""s modulus of relatively inflexible polymers herein is greater than about 207 MPa (30,000 psi), more preferably greater than about 345 MPa (50,000 psi), even more preferably greater than about 517 MPa (75,000 psi).
While a wide variety of polymers can be used in the blend, at least one polymer being relatively flexible as compared to the other polymer (preferably such that the Young""s moduli of the two polymers differ by at least about 100 MPa, more preferably, at least about 300 MPa, and even more preferably at least about 500 MPa, it is preferred that the blend has a Young""s modulus of about 34 MPa (5,000 psi) to about 345 MPa (50,000 psi), more preferably about 69 MPa (10,000 psi) to about 276 MPa (40,000 psi), even more preferably about 103 MPa (15,000 psi) to about 207 MPa (30,000 psi).
One advantage of utilizing blends is greater formulation latitude that they provide. That is, changes in a wide variety of physical properties of films comprising the blends can be effectuated, for example, by varying the ratio of individual polymers in the blends. Furthermore, cost effectiveness is another advantage of utilizing blends. For example, less expensive polymers can be blended with more expensive polymers. In that way, the less expensive polymers can act as an xe2x80x9cextenderxe2x80x9d for the more expensive polymers. Also, using blends can provide advantageous synergistic effects, wherein, for a certain application, the blend can perform substantially better than either polymer by itself for the same application.
Any suitable polymer chemistries can be used in the blends. For example, polyolefin (e.g., polypropylene and polyethylene), polyester (e.g., polyethylene terephthalate), and polyamide (i.e., nylon) polymer chemistries are suitable. It is preferred that the polymers in the blend are compatible (i.e., there is no evidence of gross phase separation of the polymers to an unaided human eye at room temperature). Compatibility is preferably evidenced by the blend exhibiting a single melting temperature and/or each region of discontinuous phase in the blend, or film therefrom (the measurement is substantially the same for both the blend and film), having a diameter of 100 nanometers or less, more preferably about 20 nanometers or less, as measurable using Scanning Electron Microscopy. Accordingly, preferably, each of the polymers in the blends has substantially the same chemistry (i.e., the polymers are derived from the same monomer units) as the other polymer(s) (e.g., all of the polymers in a blend are polypropylene, all of the polymers in a blend are polyester, or all of the polymers in the blend are polyamide).
In one embodiment, the blend comprises at least two polypropylene polymers, preferably consisting essentially only of polypropylene polymers. Accordingly, reference is made to terms that will be used hereinafter, as defined below:
xe2x80x9cPolypropylene polymerxe2x80x9d refers to a polymer derived from at least about 50 weight % propylene monomers. Preferably, polypropylene polymers of the present invention are derived from at least about 75 weight % propylene monomers, more preferably at least about 95 weight % propylene monomers, most preferably about 100% propylene monomers.
Preferred polypropylene polymers of the present invention have controlled stereoregularity (i.e., such polypropylene polymers have a certain proportion of, for example, isotactic and syndiotactic structures).
xe2x80x9cStereoregularxe2x80x9d polymers, as defined by Hawley""s Condensed Chemical Dictionary (12th Edition), are those whose molecular structure has a definite spatial arrangement, rather than the random and varying arrangement that characterizes an amorphous polymer. Stereoregular structures include isotactic and syndiotactic structures. In general, polymers can include more than one type of structure throughout its chain length. For example, polymers can include stereoregular, isotactic, and syndiotactic structures, as well as amorphous, atactic structures, or combinations thereof.
xe2x80x9cIsotacticxe2x80x9d polymers, as defined by Hawley""s Condensed Chemical Dictionary (12th Edition), are those whose structure is such that groups of atoms that are not part of the backbone structure are located either all above, or all below, atoms in the backbone chain, when the latter are all in one plane.
xe2x80x9cSyndiotacticxe2x80x9d polymers, as defined by Hawley""s Condensed Chemical Dictionary (12th Edition), are those whose structure is such that groups of atoms that are not part of the backbone structure are located in some symmetrical and recurring fashion above and below the atoms in the backbone chain, when the latter are all in one plane.
xe2x80x9cAtacticxe2x80x9d polymers, as defined by Hawley""s Condensed Chemical Dictionary (12th Edition), are those whose structure is such that groups of atoms are arranged randomly above and below the backbone chain of atoms, when the latter are all in one plane. It is generally understood that substantially atactic polymers are amorphous, amorphous polymers generally lacking a well-defined melting point.
The structure of a polymer can be determined using any suitable method. For example, carbon-13 Nuclear Magnetic Resonance can be used to determine the tacticity of a polymer. To evaluate the polymers using carbon-13 NMR, for example, the test method described in the Test Methods, infra, can be used.
xe2x80x9cRelatively flexiblexe2x80x9d polypropylene polymers are those that are more flexible than the other polymer(s) in the blend. In general, relatively flexible polypropylene polymers will have higher proportions of comonomers (e.g., alpha-olefins, such as 1-octene or 1-hexene) and/or higher proportions of atactic units. Preferably, the flexible polypropylene polymers are at least about 20% atactic, more preferably at least about 25% atactic, even more preferably at least about 30% atactic. It is preferred, however, that the majority of the polymer structure is crystalline. Thus, such polymers are typically less than about 50% atactic. Also, those polypropylenes that are polymerized using a metallocene catalyst system (e.g., those described in PCT Publication No. WO096/26967A) tend to be more flexible than those polymerized using Ziegler Natta catalyst systems (e.g., those described in European. Patent No. 0 475 306).
Examples of such relatively flexible polypropylene polymers include: REXFLEX FPO W101 (commercially available from Huntsman Chemical Corporation; Houston, Tex.), formerly available from Rexene Products; Dallas, Tex. under the trade designation REXFLEX D100 and those described in copending U.S. patent application Ser. No. 08/956,880 entitled xe2x80x9cElastic Polypropylenes and Catalysts for Their Manufacture.xe2x80x9d
xe2x80x9cRelatively inflexiblexe2x80x9d polypropylene polymers are those that are less flexible than the other polymer(s) in the blend. Typically, the relatively inflexible polypropylene polymers are mostly isotactic, syndiotactic, or a combination thereof. Preferably, such polymers are isotactic. Preferred relatively inflexible polypropylene polymers are at least about 80% isotactic and/or syndiotactic. More preferably, relatively inflexible polypropylene polymers are at least about 95% isotactic and/or syndiotactic. Most preferably, relatively inflexible polypropylene polymers are essentially isotactic and/or syndiotactic (i.e., at least about 99% isotactic and/or syndiotactic, preferably 100% isotactic and/or syndiotactic).
A wide variety of relatively inflexible polypropylene polymers are readily available, many under the tradenames: FINA (Fina Oil and Chemical Co.; Dallas, Tex.) and ESCORENE (Exxon Polymers; Houston, Tex.). Examples of such inflexible propylene polymers include: FINA 3374 (Fina Oil and Chemical Co.), ESCORENE 1024E3 (Exxon Polymers), ESCORENE 2172E1 (Exxon Polymers), ESCORENE 4792E1 (Exxon Polymers), and ESCORENE 6114E1 (Exxon Polymers).
Each of the relatively flexible and relatively inflexible polypropylene polymers can also be derived from monomers other than propylene. For example, other copolymerizable monomers include xcex1-olefins (e.g., ethylene, 1-hexene, 1-butene, 1-octene, etc.). While these monomers can be included, it is preferred that their amounts be minimized so as not to decrease the overall melting point of the blend. Preferably, such other copolymerizable monomers are present in amounts of about 10 weight % or less, more preferably about 5 weight % or less, and most preferably about 1 weight % or less, based on total monomer weight.
In another embodiment, the blend comprises at least two polyester polymers, preferably consisting essentially only of polyester polymers. For example, polyethylene terephthalate can be utilized as the relatively inflexible polymer and a polyester elastomer can be utilized as the relatively flexible polymer. Examples of such polyester elastomers are HYTREL G3548W and HYTREL G4074, both commercially available from DuPont Polymers; Wilmington, Del.
In another embodiment, the blend comprises at least two polyamide polymers, preferably consisting essentially only of polyamide polymers. One of the polyamide polymers is more flexible than the other polyamide polymer.
In yet another embodiment, the blend comprises at least two polyethylene polymers, preferably consisting essentially only of polyethylene polymers. While the melting temperatures of polyethylenes are typically not as high as those chemistries previously discussed, such blends are suitable for use in environments where the temperature is less than the melting temperature of each individual polymer in the blend. For example, auto aftermarket painting temperatures are typically less than the melting temperatures of polyethylenes. Many other polymer chemistries will be apparent to those of skill in the art and are within the scope of the appended claims.
Each of the relatively flexible and relatively inflexible polymers is preferably present in an amount of about 20 weight % to about 80 weight % based on total weight of the blend. More preferably, each of the relatively flexible and relatively inflexible polymers is present in an amount of at least about 40 weight % based on total weight of the blend.
Advantageously, blends of the present invention can be readily formed into flexible films and exhibit several properties that make them useful in applications, such as in tape backings. Such tape backings can be made into adhesive tapes using any suitable method. These tapes are potentially useful for automobile paint masking, outdoor graphics displays, outdoor lane marking, and industrial applications, especially those where exposure to elevated temperatures is necessary.
The present blends and films therefrom exhibit at least one of the properties described below. Many of these properties are highly desirable for automobile paint masking tapes, for example.
xe2x80x9cEnvironmental Friendlinessxe2x80x9d: Preferred tape backing compositions, films and tapes therefrom essentially do not contain polyvinyl chloride (i.e., they are essentially chloride-free). Most typically, the present blends do not contain any polyvinyl chloride. Thus, when incinerated, such blends do not produce by-products resulting from the presence of polyvinyl chloride, the presence of which results in special handling concerns.
xe2x80x9cMinimal or No Ghostingxe2x80x9d: Ghosting is defined in paint masking applications as occurrences where a tape is applied, sent through a painting process that includes heating, and, upon removal, leaves a residue that is visible to the unaided human eye and the residue is not removable with solvent wipes. Preferably, ghosting of films and tapes comprising the tape backing compositions is minimal. That is, the amount of ghosting is less than that seen with conventional polyvinyl chloride auto paint masking tapes. Most preferably, however, the tapes comprising the present blends exhibit no ghosting.
xe2x80x9cEssentially Free of Plasticizersxe2x80x9d: In order to minimize ghosting, preferred embodiments of the invention do not contain plasticizers. The absence of plasticizers minimizes migration of such plasticizers to adjacent substrates, where they can degrade the substrate. If present, however, it is preferred that the proportion of plasticizers in the total film is about 3 weight % or less.
xe2x80x9cMinimal Neckingxe2x80x9d: Preferably, films comprising the tape backing compositions of the present invention exhibit a minimal level of necking. xe2x80x9cNeckingxe2x80x9d refers to a films tendency to yield irrecoverably, inducing strain in the film. Such strain can result in irregular tape lines during application. Preferably, the films exhibit less than about 5% necking when tested according to the xe2x80x9cUltimate Tensile Strengthxe2x80x9d test, infra. More preferably, however, 0% necking is exhibited. As such, preferably the films do not exhibit a yield point when tested according to ASTM D882-95a, infra.
xe2x80x9cRelatively High Stress Relaxationxe2x80x9d: Preferably, films comprising the tape backing compositions of the present invention exhibit excellent stress relaxation, enabling easy application to irregular surfaces. Once applied, the films readily adhere to (i.e., they do not readily delaminate from) such irregular surfaces. Accordingly, it is preferred that the films exhibit at least about 20%, more preferably 40%, stress relaxation when tested at 10% elongation according to the xe2x80x9cStress Relaxationxe2x80x9d test, infra. Similarly, it is preferred that the films exhibit at least about 35%, more preferably 55%, stress relaxation when tested at 57% elongation according to the xe2x80x9cStress Relaxationxe2x80x9d test, infra.
xe2x80x9cHand-Tearablexe2x80x9d: It is also preferred that the present films are readily hand-tearable. While this is a subjective test, the preferred films are at least as easy to tear by hand as conventional polyvinyl chloride films used in auto paint masking applications.
xe2x80x9cHeat-Resistantxe2x80x9d: It is also preferred that the present films are heat-resistant. When used in auto paint masking tapes, for example, the films should be resistant to temperatures of about 149xc2x0 C. (300xc2x0 F.), or for the auto aftermarket, about 93xc2x0 C. (200xc2x0 F.). Preferably, the films are heat-resistant to temperatures of as high as about 154xc2x0 C. (310xc2x0 F.). As evidence of heat resistance, the films preferably exhibit a minimal degree of shrinking when exposed to relatively high temperatures. Thus, they are dimensionally stable at high temperatures, maintaining protection of the surface to which they are adhered.
As such, it is most preferred that the films do not shrink when exposed to temperatures as high as about 93xc2x0 .C (200xc2x0 F.), more preferably temperatures as high as 149xc2x0 C. (300xc2x0 F.), and most preferably temperatures as high as 154xc2x0 C. (310xc2x0 F.). However, shrinkage of as much as 5%, when tested according to ASTM D1204, infra, may be tolerable in some applications. Accordingly, it is preferred that the films do not exhibit more than about 5% shrinkage, more preferably less than about 3% shrinkage, and even more preferably less than about 1% shrinkage.
To obtain heat-resistant films, it is preferred that each polymer in the blend has a melting temperature of at least as great as the temperature at which it is to be used. More preferably, each polymer in the blend has a melting temperature of at least about 10xc2x0 C. greater than the temperature at which it is to be used.
xe2x80x9cPaint-Resistantxe2x80x9d: Furthermore, it is preferred that the present films are resistant to paint. That is, solvent paints can be applied to one side of the film without bleeding through to the opposite side of the film.
Blending
Blending of the polymers is done by any method that results in a substantially homogenous distribution of the relatively flexible polymer and relatively the inflexible polymer. The polymers can be blended using several methods. In particular, the polymers can be blended by melt blending, solvent blending, or any suitable physical means.
For example, the polymers can be melt blended by a method as described by Guerin et al. in U.S. Pat. No. 4,152,189. That is, all solvent (if used) is removed from each polymer by heating to a temperature of about 150xc2x0 C. to about 175xc2x0 C. at a pressure of about 5 Torr to about 10 Torr. Then, the polymers are weighed into a vessel in the desired proportions. The blend is then formed by heating the contents of the vessel to about 175xc2x0 C., while stirring.
Although melt blending is preferred, the adhesive blends of the present invention can also be processed using solvent blending. In that case, the polymers in the blend should be substantially soluble in the solvents used.
Physical blending devices that provide dispersive mixing, distributive mixing, or a combination of dispersive and distributive mixing are useful in preparing homogenous blends. Both batch and continuous methods of physical blending can be used. Examples of batch methods include BRABENDER (using a BRABENDER PREP CENTER, available from C.W. Brabender Instruments, Inc.; South Hackensack, N.J.) or BANBURY internal mixing and roll milling (using equipment available from FARREL COMPANY; Ansonia, Conn.). Examples of continuous methods include single screw extruding, twin screw extruding, disk extruding, reciprocating single screw extruding, and pin barrel single screw extruding. The continuous methods can include utilizing both distributive elements, such as cavity transfer elements (e.g., CTM, available from RAPRA Technology, Ltd.; Shrewsbury, England) and pin mixing elements, static mixing elements and dispersive elements (e.g., MADDOCK mixing elements or SAXTON mixing elements as described in xe2x80x9cMixing in Single-Screw Extruders,xe2x80x9d Mixing in Polymer Processing, edited by Chris Rauwendaal (Marcel Dekker Inc.: New York (1991), pp. 129, 176-177, and 185-186).
Other Additives
Other additives may also be blended into the tape backing compositions and flexible films and tapes therefrom, depending on the desired application. For example, flame retardants, fillers (e.g., calcium carbonate, silicates, talc, and chalk), dyes, pigments, and nucleating agents can be added as well known to one of ordinary skill in the art.
Application of the Tape Backing Composition
The tape backing composition is readily formed into a flexible film, as described below. The film can be utilized in any suitable application. For example, the film can be used in sheeting products (e.g., decorative, reflective, and graphical), labelstock, and tape backings. Generally such films have a thickness of about 25.4 xcexcm to about 127 xcexcm (about 1 mil to about 5 mil).
Tape backing compositions according to the present invention can be utilized to form tape, for example. An adhesive is applied to at least one side of the backing. Preferably the adhesive is able to withstand the same temperatures as the film backing. Any suitable adhesive chemistry can be utilized. For examples, acrylate adhesives, crosslinked rubber-based adhesives, and alpha-olefin adhesives can be used. Such adhesives may be crosslinked to further improve the high temperature performance of the adhesive. Any suitable crosslinking method (e.g., exposure to radiation, such as ultraviolet or electron beam) or crosslinker additive (e.g., phenolic and silane curatives) may be utilized.
When double-sided tapes are formed, an adhesive is coated onto at least a portion of both sides of the backing. Alternatively, a release material (e.g., low adhesion backsize) can be applied to the opposite side of the backing, if desired. Advantageously, the adhesive and/or release material, for example, can be coextruded with the film backing for ease of processing.
Films can be formed using methods well known to one of ordinary skill in the art. For example, the film can be formed using melt extrusion techniques. The tape backing composition can be formed into a film or coating by either continuous or batch processes. An example of a batch process is the placement of a portion of the tape backing composition between a substrate to which the film or coating is to be adhered and a surface capable of releasing the adhesive film or coating to form a composite structure. The composite structure can then be compressed at a sufficient temperature and pressure to form a coating or layer of a desired thickness after cooling. Alternatively, the tape backing composition can be compressed between two release surfaces and cooled.
Continuous forming methods include drawing the tape backing composition out of a heated film die and subsequently contacting the drawn composition to a moving plastic web or other suitable substrate. A related continuous method involves extruding the tape backing composition and a coextruded release material and/or adhesive from a film die and cooling the layered product to form an adhesive tape. Other continuous forming methods involve directly contacting the tape backing composition to a rapidly moving plastic web or other suitable preformed substrate. Using this method, the tape backing composition is applied to the moving preformed web using a die having flexible die lips, such as a conventional film or sheeting die. After forming by any of these continuous methods, the films or layers can be solidified by quenching using both direct methods (e.g., chill rolls or water baths) and indirect methods (e.g., air or gas impingement).
Although coating out of solvent is not preferred, the tape backing compositions can be coated using a solvent-based method. For example, the tape backing composition can be coated by such methods as knife coating, roll coating, gravure coating, rod coating, curtain coating, and air knife coating. The coated solvent-based tape backing composition is then dried to remove the solvent. Preferably, the coated solvent-based tape backing composition is subjected to elevated temperatures, such as those supplied by an oven, to expedite drying.
Films and articles therefrom can, optionally, be heat-treated to further improve dimensional stability of the films and articles. Any suitable heat treatment and method thereof can be used. Preferably, however, the film or article to be treated is unrestrained during the heat treatment. For example, the film or article can be passed over heated rolls. As another example, the film or article can be passed between rolls and heated, such as by a radiant heater.
The tape backing compositions, films, and tapes therefrom are exemplified in the following examples. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight unless indicated otherwise.